Antithyroid Activity Elicited by the Ingestion of Pure Progoitrin, a Naturally Occurring

Foodstuffs of various sorts have been implicated as a cause of goiter for many years. Only by the discovery of Chesney, Clawson and Webster in 1928 that cabbage feeding would result in thyroid enlargement in laboratory animals (1) were these vague hypotheses started on a firm experimental footing, however (for detailed review see Reference 2). Although various articles of diet have been reported to produce goiter in diverse animal species since that time, studies employing the acute inhibition of thyroidal radioiodine accumulation indicated that only a relatively small number of foods possessed antithyroid activity in man (3). Of these, rutabaga was consistently the most potent. Eventually it was possible to isolate and identify the active agent in this species, 1-5-vinyl, 2-thiooxazolidone (4), more recently termed "goitrin" (5). Goitrin has been identified in the seeds of most Brassicae but until recently in the edible parts of only rutabaga and turnip. It has now been reported that goitrin has been detected in the edible portions of cabbage, kale and rape (6, 7). As yet no other naturally occurring antithyroid compound with pathogenetic significance for man is known to exist. Very early in the studies isolating goitrin it became apparent that this substance did not exist in the free state but was bound to a precursor from which it could be liberated by a crude enzyme preparation, myrosin, prepared from crucifers. Myrosin supposedly is or contains a specific thioglycosidase which hydrolyzes mustard oil thioglycosides (8).